This invention relates to an automatic performing system in which a performance is reproduced and/or recorded by using correct performance information, and in which an error in the transmission is corrected while the performance information is transmitted and received between performance information transmitting and receiving units. This invention more particularly relates to an automatic performing system that is applied to the transmission of performance information on a real-time basis while the performance is in progress, and not to packet transmission in which errors are detected by using check sums.
Known are various conventional automatic performing systems: an automatic performing system in which performance information is transmitted from a master instrument to a slave instrument; an automatic performing piano in which performance information is read from a floppy disc and is transmitted from a main controller to a sub controller for actuating key drive solenoids; and other automatic performing systems for reproducing performance by transmitting performance information from a performance information transmitting unit to a performance information receiving and reproducing unit. In these prior art systems, the transmission of performance information is designated in one direction only: the master instrument and the main controller transmit performance information to the slave instrument and the sub controller, respectively, on a real-time basis. Therefore, errors cannot be detected by using check sums as in the case of packet transmission. Instead, the receiving unit such as the slave instrument or the sub controller provided with a structure for detecting errors transmission by using parity check, such that if an error found in the transmission of performance information, received performance information is discarded.
In the prior art systems, the discard of incorrectly received performance information causes several problems. For example, when an incorrectly received off-event is discarded, an on-event cannot be terminated, undesirably continuing sound emission. Such problems result in undesirable noise interfering with other sound emission in an electronic instrument, for example. In the automatic performing piano, the key drive solenoids are damaged due to their continued actuation.
Even when the automatic performing systems have no structure for detecting errors and discarding incorrectly received performance information, problem still occurs. For example, if the transmission of key number data in event data has an error, the on-event of the corresponding key misses the counterpart off-event. Consequently, the performance information cannot be correctly processed, thereby damaging the key drive solenoids and causing other aforementioned problems.
In the prior-art systems, packet transmission is a known communication method in which errors are detected by using a check sum covering a predetermined number of bytes of transmitted or received data. If this method is applied to the automatic performing systems, however, the reproduction of performance information is interrupted for check. Consequently, the check function in packet transmission systems cannot be applied to the automatic performing systems in which data is transmitted on a real-time basis. Further in the packet transmission systems, data is transmitted by handshaking and a port is required for the handshaking. Automatic performing systems obviating the need for such a port have been desired.
In the prior-art automatic performing systems for reproducing performance by transmitting performance information from the performance information transmitting unit to the receiving unit, the incorrectly received performance information causes problems. The same problems also occur in automatic performing systems for recording performance information. Specifically, if performance information is incorrectly received and an on-event does not have the counterpart off-event, performance information is incorrectly recorded. When the incorrectly recorded performance information is reproduced, key drive solenoid damage or other aforementioned problems occur even if the recorded performance information is correctly received for reproduction.